1. Field of Invention
Electrical bus bars and electrical switchboards employing the same.
2. Description of Prior Art
This invention relates to bus bars for use in relatively large switchboards and to the manner of their incorporation in the switchboard.
Heretofore such bus bars have been in the form of aluminum or copper straps which are first cut to length and then provided with sets of holes through which bolts are received for mounting the bus bars on suitable supports within a cabinet, for connecting them to each other, and for mounting electrical cable connectors thereon. Usually the locations of the holes are predetermined for specific arrangements, the holes being punched by the manufacturer at precise predetermined positions.
The use of holes in different positions along the bus bars limits the possible positions of the bus bars relative to each other and to supporting structure to the one specific arrangement of the original design. Consequently, for each different type and size of switchboard, holes have to be specially laid out and punched in the bus bars.
Another undesirable feature of prior bus bar designs is that the current carrying capacity of the bars is not uniform for all cross sections throughout its length as the total cross section for conducting metal is reduced at those areas in which the holes are provided relative to those areas in which no hole is provided. Accordingly, assuming a bar of uniform thickness and overall width, to provide an amount of conducting cross section at the location of the holes sufficient to meet the rated maximum current carrying capacity of the bar results in an excess of conducting cross section at the imperforate portions, and a resultant waste or inefficient use of the metal.
Considerable layout time and expense is involved in positioning and punching the selected holes.